Sharapova is 34-7 and has won two titles this season, which leaves her far from satisfied.

“Even when I’ve been healthy, little things here and there have limited me,” she said.

She feels fortunate to be second in the rankings behind Williams, who will go into the U.S. Open trying to win the first Grand Slam since Steffi Graf in 1988.

“Consistency is much underrated, but it goes a long way,” Sharapova said. “She has an incredible power to do that. The competitive thing is very unique. She has that extra gear that everybody wants to get.”